Scenario
Primary alluminiun factory: 8 Rectifier Transformers (Sweden)
Nameplate data of transformers:
Manufact: xxx
Year: 1930
Power [MVA]: 19
Voltage [KV]: 13
Oil Mass [Kg]: 15.000
Oil type: mineral blended
Solution
Selective depolarization treatment (Chedcos) in order to remove the DBDS + dehalogenation treatment (CDP Process) in orderr to remove the PCBs both from oil and transformers. The treatments were performed on-site, on-line and on-load (transformer in servise and under charge during the treatment).
The treatments were carried out with the following guarantees: DBDS < 10 mg/kg, PCBs < 2 mg/Kg restoring also the other oil parameters as suggested by IEC 60422 ed. 4, 2013
Before the treatments |
After the treatments |
|
| PCBs [mg/Kg] | 29 | 0,37 |
| DBDS [mg/Kg] | 18 | < 5 |
| IFT [mN/m] | 24 | 42 |
| CCD Test | corrosive | NOT corrosive |
| TAN [mg KOH/g] | 0,34 | 0,01 |
| DF | 0,230 | 0,002 |
